Radioactive dating exercises

If half of the uranium has decayed, then the rock has an age of one half-life of uranium-235, or about 4.5 × 10H dating has been used to verify the stated vintages of some old fine wines.Carbon-14 (half-life is 5,370 y) is particularly useful in determining the age of once-living artifacts (e.g., animal or plant matter).Scientists were also able to use radiocarbon dating to show that the age of a mummified body found in the ice of the Alps was 5,300 y.

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If a once-living artifact is discovered and analyzed many years after its death, with the remaining carbon-14 compared to the known constant level, an approximate age of the artifact can be determined.

Using such methods, scientists determined that the age of the Shroud of Turin (made of linen, which comes from the flax plant, and purported by some to be the burial cloth of Jesus Christ; Figure 11.3 "Shroud of Turin") is about 600–700 y, not 2,000 y as claimed by some.

For example, if a thyroid tumor is detected, a much larger infusion (thousands of rem, as opposed to a diagnostic dose of less then 40 rem) of iodine-131 could help destroy the tumor cells.

Similarly, radioactive strontium is used to not only detect but also ease the pain of bone cancers.

A tiny amount of carbon-14 is produced naturally in the upper reaches of the atmosphere, and living things incorporate some of it into their tissues, building up to a constant, although very low, level.

Once a living thing dies, however, it no longer acquires carbon-14, and as time passes, the carbon-14 that was in the tissues decays.

Eggs and some meat, such as beef, pork, and poultry, can also be irradiated.

Contrary to the belief of some people, irradiation of food make the food itself radioactive.

After incorporating radioactive atoms into reactant molecules, scientists can track where the atoms go by following their radioactivity.

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